This is a continuation of an amniocentesis registry begun in September, 1971. The purpose is to monitor amniocentesis and its consequences to mother and fetus through pregnancy, delivery, and the baby's first year of life. This procedure concernes itself with the recording of the actual procedure, the experience of the laboratory in processing fluid and cells, the outcome of the pregnancy, and the physical well-being of the babies born after amniocentesis. Appropriate controls obtained at the time of these procedures will be matched according to the previously prescribed method, developed by the NICHD biostatistics department.